The present invention relates to a process for correcting an ascertained unbalance on a rotor, and to a device for this purpose.
When rotors are balanced, first of all, their unbalance is ascertained in an unbalance measuring machine or balancing machine. The unbalance is generally related to one or more correction planes and determined on the basis of magnitude and angular position. Consequently, a polar unbalance correction is possible. If the unbalance correction on rotors can only be carried out at certain sites distributed along the circumference, the correction is carried out at sites that are suitable for that purpose in components of the correction vector. In the case of armatures for electric machines, these are the pole shoes that are connected by webs to the armature core and between which the copper wire windings are located. In this process, the pole shoes should be weakened as little as possible and, in particular, milling through or grinding down to the windings should be avoided under all circumstances. Moreover, the component correction should be carried out in a angle work step at the sites suitable for this purpose.
A process and a device of the type mentioned above are known from DE 42 29 521 A1. Here, the component correction is carried out on an electric armature in a single work step. This familiar process uses three correction tools mounted on a tool spindle. For purposes of removing material, they are moved linearly in the axial direction of the tool spindle as well as tangentially to the rotor, depending on the unbalance, and they are also moved linearly in the radial direction in order to advance into the rotor. With this known process, the rotor is turned to such an extent that the middle axis of the pole shoe from which the greatest correction mass is to be removed is aligned with the middle of the three correction tools. Before the correction procedure is carried out, the correction tools with the tool spindle are moved tangentially by a path determined on the basis of the ascertained unbalance that is to be corrected. The rotor follows the correction tools by being continuously related around its axis by a calculated angle that corresponds to the movement path and to the movement direction of the middle correction tool. Subsequently, for purposes of the unbalance correction, the correction tools are moved along a linear path radially to the rotor so that the correction tools carry out the material removal at a calculated penetration depth. A drawback of the prior art process is that the rotor has to follow the movement of the correction tools by being rotated around its axis.
Accordingly, one of the objectives of the present invention is a process and a device of the type mentioned above for the correction of an ascertained unbalance, whereby a precise unbalance correction is carried out in one single work step using the simplest possible set-up.
The present invention has the advantage that it is not necessary for the rotor to follow by being turned around its axis, so that the set-up of the device and the execution of the process are considerably simplified. The rotor armature during the component correction in two machining steps, remains in a position corresponding to the division. This is especially advantageous when the unbalance measurement and the unbalance correction are carried out on different machines or in different stations of a unit, since the rotor only has to be placed in one of its positions corresponding to the division and a continuous turning into machining positions is not necessary. Consequently, a turning device for this purpose is not necessary. According to the invention, the angular position setting of the correction unbalance is carried out by just two correction tools, so that a third correction tool located between them is not necessary for this purpose and, at most, can be provided in order to influence the magnitude of the correction unbalance. It has proven to be especially advantageous that the angular position setting can be achieved over a large angle range corresponding to the division by means of small tangential movement paths of the correction tool set. The slanted advancing of the correction tools leads to a larger carriage length and thus to better utilization of the available pole shoe material. Furthermore, when the pole shoe between the correction tools is not being machined, if necessary, a second correction step is easily possible. Leaving this pole shoe free advantageously opens up the possibility of supporting the rotor on at least this pole shoe or of using this pole shoe for alignment of the rotor corresponding to the division in the lock-in positions defined by the number of pole shoes.
In an advantageous embodiment of the invention, the correction tools advance into the rotor to about the middle with respect to the correction sites, whereby at the maximum advancing depth, the machining profile lies in the middle relative to the web axis. In this manner and through the slanted advancing, for example, at 45xc2x0, the appertaining correction site, e.g. a pole shoe of an electric armature, is weakened as little as possible.
According to the invention, another embodiment provides that the correction components correct an unbalance vector that lies within an angle range corresponding to a correction site division. The angle range extends on both sides of a possible correction site or on both side of a middle plane between two possible correction sites. With an even number as well as with an odd number of intermediate possible correction sites, only one rotation of the rotor corresponding to the division around a lock-in position is needed each time when the unbalance vector to be corrected lies adjacent to the indicated angle range. The invention can be used for an even and an odd number of correction sites of the rotor.